PIPE SHELL MADE OF LOW-CARBON MICROALLOYED STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/24 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention concerns the metallurgy field. Particularly it concerns manufacturing of pipe shell of diameter from 100 till 180 mm, intended for producing seamless pipe for various purposes. Pipe shell is made of steel, which consists in mass % of: C-(0.16÷0.22), Mn-(1.30÷1.70), Si-(0.35÷0.55), V-(0.10÷0.20), Mo-(0.06÷0.08), N-(0.0054÷0.015), As-(0.0001÷0.03), Sn-(0.0001÷0.02), Pb-(0.0001÷0.01), Zn-(0.0001÷0.005), S-(0.005÷0.035), iron and inevitable admixtures, in ratio: (As+Sn+Pb+5×Zn)≤0.07; 0.54≤(C+Mn/6+Mo+V)≤0.76, hot-rolled and normalised. Blank has ferrite-pearlite structure, effective grain size is 5-10 points, macrostructure is: center porosity, spot inhomogeneity, liquating square is not more than 2 points, undershrinked sweat is not more than 1 points; liquating strip is not more than 1 point, nonmetallic: spot sulphides, spot oxide, stitch oxide, fragile silicate, plastic silicate, unstrained silicate - not more than 2.5 points for every kind, mechanical properties after normalisation: tensile strength is 550-780 N/mm², yield strength is not less 410 N/mm², percentage elongation is not less than 22%, impact strength KU (-20°C) is not less than 35 J. In capacity of admixture steel also contains in mass %: P not more than 0.035; Cr not more than 0.30; Ni not more than 0.30; Cu not more than 0.30.

EFFECT: heightened level of consumer behavior for pipe shell.

3 cl, 2 ex